Vertical phosphorus migration in biosolids-amended soils : concentrations in soils and leachates.

The impacts of biosolids land application on soil phosphorus and subsequent transfer to aquatic ecosystems in the condition of the minimal slope were assessed. Soil, representing typical "Non response" Ontario soil, was amended with anaerobically digested biosolids at a rate of 8 tonnes/ha. Over five months, soil samples from two different depths were sequentially fractionated to determine various inorganic and organic phosphorus pools in order to evaluate phosphorus vertical migration within a soil profile. Soil leachate was analyzed for soluble reactive phosphorus and added to the aquariums mimicking receiving surface waters. Water from aquariums was tested for the presence of eutrophication. The results indicated that biosolids application did not significantly affect phosphorus concentrations in soil and did not cause phosphorus vertical migration. The concentrations of soluble reactive phosphorus also were not affected by biosolids. No signs of eutrophication were observed in receiving waters.

Vertical phosphorus migration in biosolids-amended soils : concentrations in soils and leachates.

The impacts of biosolids land application on soil phosphorus and subsequent transfer to aquatic ecosystems in the condition of the minimal slope were assessed. Soil, representing typical "Non response" Ontario soil, was amended with anaerobically digested biosolids at a rate of 8 tonnes/ha. Over five months, soil samples from two different depths were sequentially fractionated to determine various inorganic and organic phosphorus pools in order to evaluate phosphorus vertical migration within a soil profile. Soil leachate was analyzed for soluble reactive phosphorus and added to the aquariums mimicking receiving surface waters. Water from aquariums was tested for the presence of eutrophication. The results indicated that biosolids application did not significantly affect phosphorus concentrations in soil and did not cause phosphorus vertical migration. The concentrations of soluble reactive phosphorus also were not affected by biosolids. No signs of eutrophication were observed in receiving waters.

Vertical phosphorus migration in a biosolids-amended sandy loam soil in laboratory settings: concentrations in soils and leachates

The impacts of biosolids land application on soil phosphorus and subsequent vertical migration to tile drainage were assessed in a laboratory setup. Soil, representing typical “nonresponse” Ontario soil as specified by Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA), was amended with anaerobically digested biosolids at a rate of 8Mgha−1 (dry weight). Over five months, these amended soil samples from two different depths were sequentially fractionated to determine various inorganic and organic phosphorus pools in order to evaluate phosphorus vertical migration within a soil profile. Soil leachate was analyzed for soluble reactive phosphorus.The results indicated that biosolids application did not significantly affect phosphorus concentrations in soil and did not cause phosphorus vertical migration. The concentrations of soluble reactive phosphorus also were not significantly affected by biosolids.

Vertical phosphorus migration in a biosolids-amended sandy loam soil in laboratory settings: concentrations in soils and leachates

The impacts of biosolids land application on soil phosphorus and subsequent vertical migration to tile drainage were assessed in a laboratory setup. Soil, representing typical “nonresponse” Ontario soil as specified by Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA), was amended with anaerobically digested biosolids at a rate of 8Mgha−1 (dry weight). Over five months, these amended soil samples from two different depths were sequentially fractionated to determine various inorganic and organic phosphorus pools in order to evaluate phosphorus vertical migration within a soil profile. Soil leachate was analyzed for soluble reactive phosphorus.The results indicated that biosolids application did not significantly affect phosphorus concentrations in soil and did not cause phosphorus vertical migration. The concentrations of soluble reactive phosphorus also were not significantly affected by biosolids.

Macrostructural and Microstructural Properties of Residual Soils as Engineered Landfill Liner Materials

ABSTRACT This study assessed the performance of residual soils with regard to their macrostructural and microstructural properties and compatibility with leachate in pursuit of exploring alternative cost-effective and efficient landfill liner materials. A series of laboratory investigations was conducted on three residual soil samples by using tap water and leachate as permeation fluid to achieve the objectives of the study. The zeta potential measurements revealed that the presence of multivalent cations in the leachate decreased the diffuse double layer (DDL) thickness around the soil particles. The reduced DDL thickness caused a decrease in Atterberg limits of soil-leachate samples and changes in the classification of fine fractions. Additionally, the effects of pore clogging attributed to chemical precipitation and bioclogging were responsible for the reduction in measured hydraulic conductivities of soil-leachate samples. These effects can be clearly observed from the field-emission scanning electron microscopy images of soil-leachate samples with the appearance of less visible voids that led to a more compact and dense structure. The formation of new non-clay minerals and associated changes in the Al and Si ratio as reflected in the x-ray diffraction diffractograms and energy-dispersive x-ray analyses, respectively, were attributed to the effects of chemical precipitation. This study concluded that S1 and S2 residual soil samples are potential landfill liner materials because they possess adequate grading characteristics, adequate unconfined compressive strength, low hydraulic conductivity, and good compatibility with leachate. In contrast, the S3 sample requires further treatment to enhance its properties in order to comply with the requirements of landfill liner materials.

Occurrence of Pharmaceutical Compounds in Groundwater from the Gran Canaria Island (Spain)

The presence of pharmaceutical compounds in the whole environment is a growing concern. These compounds might be present in the effluents of wastewater treatment plants and, hence, irrigation with treated sewage may be a source of groundwater pollution. The volcanic aquifer that lies NE of Gran Canaria (Spain) was studied to address the relationship of the occurrence of pharmaceutical compounds and a golf course that has been irrigated with regenerated water since 1973. Of the 14 analyzed groundwater samples, five wells were chosen to perform annual monitoring. Irrigation water and soil leachate were also evaluated. The target analytes were atenolol, metamizole, fluoxetine, ibuprofen, nicotine, permethrin, caffeine, and their metabolite paraxanthine. The environmental risk is limited as the concentrations of the pharmaceuticals measured in the sampled wells were always below 60 ng·L−1 (lower than the detected caffeine and nicotine concentrations). Wide variations for the same wells were measured among sampling campaigns, and also among the different wells. The study points to the importance of sample conservation during transport and the need to perform analyses immediately, or to follow an in-situ extraction procedure to carry concentrated samples under better conditions.

Spatial-temporal variations in riverine carbon strongly influenced by local hydrological events in an alpine headwater stream

Headwater streams drain > 70 % of global land areas but are poorly monitored compared with large rivers. The small size and low water buffering capacity of headwater streams may result in a high sensitivity to local hydrological alterations and divergent carbon transport dynamics relative to large rivers. To assess these aspects, here we carry out a benchmark investigation on the riverine carbon dynamics in a typical alpine headwater stream (Shaliu River) on the Qinghai-Tibetan Plateau based on annual flux monitoring, in-depth seasonal sampling and hydrological event monitoring. We show that riverine carbon in the Shaliu River was dominated by dissolved inorganic carbon, peaking in the summer due to high discharge brought by the monsoon. Combining seasonal sampling along the river and monitoring of soil-river carbon transfer during spring thaw, we also show that both dissolved and particulate forms of riverine carbon increased downstream in the pre-monsoon season due to increasing contribution of organic matter derived from thawed permafrost along the river. By comparison, riverine carbon fluctuated in the summer, likely associated with sporadic inputs of organic matter supplied by local precipitation events during the monsoon season. Furthermore, using lignin phenol analysis for both riverine organic matter and soils in the basin, we show that the higher acid-to-aldehyde (Ad / Al) ratios of riverine lignin in the monsoon season reflect a larger contribution of topsoil likely via increased surface runoff compared with the pre-monsoon season when soil leachate lignin Ad / Al ratios were closer to those in the subsoil than topsoil solutions. Overall, these findings highlight the unique patterns and strong links of carbon dynamics in alpine headwater streams with local hydrological events. Given the projected climate warming on the Qinghai-Tibetan Plateau, thawing of seasonal permafrost and alterations of precipitation regimes may significantly influence the alpine headwater carbon dynamics, with cascading effects on the biogeochemical cycles of the watersheds. The alpine headwater streams may also be utilized as sentinels for climate-induced changes in the hydrological pathways and/or biogeochemistry of the small basin.